Magnetic storage devices are often included in computer systems to provide high capacity secondary storage or data archival. Magnetic tape systems are a type of magnetic storage. Magnetic tape systems are widely used because they provide high storage densities while employing low cost media.
A magnetic tape system generally comprises a recording media, magnetic tape, and a media access device known as a tape drive or tape transport that reads data from and writes data to the magnetic tape. A magnetic tape typically comprises a flexible narrow ribbon of a base material (e.g., polyester films such as polyethylene naphthalate or polyethylene terephthalate), and a magnetic material, such as a metal particulate, affixed to the base material by a binding agent (e.g:, vinyl chloride polymer). The tape drive accesses the magnetic tape as the tape passes over a set of transducers called “heads.” “Write heads” generate magnetic fields which encode data onto the tape as the tape passes over the heads. “Read heads” sense the magnetic fields of the tape's magnetic material to read data from the tape.
Magnetic tape systems are subject to a phenomenon whereby the surface of the magnetic tape adheres to a component of the tape drive, for example the tape head assembly. This phenomenon is sometimes referred to as “stiction.” A variety of conditions, including binder formulations and environmental factors, operate to promote stiction. After adhesion occurs, breaking the tape free from the heads may cause damage to the tape surface, or other severe failures including deformation or breaking of the tape media.
Linear tape systems employ multiple data tracks that run parallel to one another over the length of the tape. Such tapes often include more data tracks than the tape drive has heads. These systems use a serpentine recording method wherein a first set of data tracks is written as the tape moves across the heads in a forward direction, and a second set of data tracks is written as the tape moves across the heads in the reverse direction. Many direction reversals may be required to write a tape with hundreds or thousands of tracks, with each direction reversal necessitating a momentary halt of tape motion. Serpentine recording systems typically stop the tape at the same location at the beginning and end of tape when changing directions. Repetitively stopping the tape at the same location can cause excessive wear oh the tape at the locations where the heads contact the tape near zero velocity, and possibly result in the tape sticking to the heads.